Content count

Joined

Last visited

Community Reputation

Just a quick update.
gr5 was right, changing the flow to 115% in UM2 filament settings and to 115%-120% once the print starts seems to have fixed the problem.
I am in the middle of the large print so I cannot multiply/combine all of those into one to retest but it seems that my flow needs to be increased by over 30% to give the best results.
This also agrees with something I observed earlier. Simplify3D would calculate that I need, say, 1000g of filament for object 1 and another 500g for object 2. Previously the 2.4kg spool of XT would last 2x object 1 + 1x object 2 and there will be quite a bit of filament left. That is 2.5kg + lots of leftover material out of 2.4kg spool. The filament size seems to be correct.
I will retest with cura but I am sure that it was doing the same when I was printing with PLA.
Also of interest is that the black blobs completely disappeared. I had quite a few before (with XT only) but none now. Seriously, not a single one in over 100h of printing. No other parameters apart from the flow have changed.

I was using the extra large XT spool. 2.2kg of plastic on a giant spool :-)
It has been opened for less than 10 days.
It has a much larger radius of curvature than the normal spools so that being at the end probably does not matter too much. The radius at the end of the XL spool is larger than the radius at the beginning of normal-sized spools.
Have it sitting on bearings on a custom designed holder.

Just a quick update, running it hotter (260 degrees) and slower (75% speed) and setting material flow to 107% on the printer fixed/saved the running print. It was underextrusion.
The print took 55h to finish :-)
Then I installed a new PTFE coupler. There was not much of the original filament left but it seemed to be working fine with the original settings (255 deg, 100% speed). With a brand new spool of XT it has been working fine (30h of printing so far).
I read somewhere that the PTFE coupler does not have that much effect on XT (and ABS) but it clearly did.
I thought that the

Thanks to everybody for replies.
I have previously re-tightened the short belts (as suggested in the troubleshooting guide) but nothing changed. Doing another print right now (half-way into 40h print)...
Jonnybischof, yes that particular print has 2 shells with one sticking to the part and the other one delaminated. I also had prints with 5 shells and they were delaminating from each other and from the infill... it looked like a pack of cards.
I am using simplify3D with overlap increased to 70%. Once this print is finished I will try cura to see how it goes.
Underextrusion is possible. The PTFE coupler has seen better days but I didn't think that mattered much with XT. I have slowed down the current print to 80% (i.e. 40mm/s), increased temperature to 260 degrees and turned down the fan. Fingers crossed.
Thinking of increasing the material flow as well.
Jonnybischof, when you said that nozzle can melt the layer below if moving too slowly, does that explain the black blobs that I ocasionally get?

Hi
In my last few prints the outer walls are separating from the infill and also the layers of the wall are separating from "each other". Image below shows it nicely. The individual vertical wall-layers are quite nicely bonded in the z direction but not in x and y.
Any hints what could be wrong? Everything else looks OK.
Printing XT @ 255 degrees, 0.2mm layers, 40mm/s speed but previously I have seen the same issue with PLA.
Thanks in advance.

Regarding lifting off:
- is your bed leveling right? You can try squashing the first layer a bit more and also printing the first layer slower.
- I had to bump up my bed temperature to 75 degrees to improve stickiness. The screws under the glass plate may create an air-gap and your real glass temperature may be lower than the reading.
- I am actually printing XT in an enclosed printer (originally designed for ABS). Printing 200x200x120mm objects without lifting.

Tried the latest version on UM2. I loved all the information but I noticed two things straight away.
1. There was just noticable flicker of the LEDs (set to 100%). It may be my eyes but after I flashed the original firmware back and I could not see it any more.
2. The print (sliced with Simplify3D) was shifted towards back by 5-10mm compared to the original firmware. I noticed because the printed object was quite large (200x200mm + brim) and the nozzle hit the back left clip. Flashing back the original firmware shifted the object forward.
And another interesting "bug" present in both firmwares (this and original), the hours variable is a byte and overflows when it reaches 255h. My print is "only" 42h but during the initial heating the estimated time kept incrementing and it actually rolled over twice :-)
I suppose nobody will be doing 255h prints :-)

Will post it on the github, have to make an account first.
By the way, on linux serial port is a terminal, just like text terminals. They don't get locked automatically on opening as, in some cases, it is useful to have access to a terminal from multiple programs. For example if you are using a text terminal and someone wants to send you a message. I can also see use of this for debugging devices connected via virtual serial port.

Hi
I was printing from simplify3D (on linux) via USB to UM2 when I loaded Cura (15.06.01) to check another design. At startup Cura connected to the printer (which was already printing) which lead to head crashing into the right wall and the belt skipping and then the print resumed several centimeters to the side (in the air). While there was no damage to the printer, a 4h print was ruined.
I am not sure what Cura's default behaviour is but, as far as I know, Cura should not try to connect to a printer which is in use.
Simplify3D created the lock file var/lock/LCK..ttyACM0 meaning it needs exclusive access to the tty port. Cura should have checked for this file (and for the PID of the process which created it) before trying to connect to the printer. More details on serial port locking on linux can be found here. Unless I got everything wrong, cura should be following this.
Thoughts?

I am curious, why do you say USB printing is not recommended with the UM2?
I have found USB printing quite convenient for doing small prints or quick test prints. I have encountered no problems so far in probably over 50h of USB printing using simplify3D (I have not tried Cura yet). Much, much quicker than swapping SD cards after changing only one parameter.
As far as I know the only problem is if your computer/software crashes mid-print. But people use octoprint/octopi which is a dedicated Raspberry Pi to do printing via USB and UM2.

I am definitely not an expert but on the first and last photo these look like blobs you get during layer change. If you look at photos in this thread you will notice similar "blobs" as in your first print. Are you using Cura? I am not sure if it can do retraction during layer changes.
The middle photo shows stringing meaning you need to play with retraction, see here for hints.

After recently starting printing in ABS I am trying to figure out which retraction settings to use.
ATM I am using 4.5mm-5mm @ 40mm/s. During moves (speed = 250mm/s) some plastic oozes out of the nozzle and stays on the print. Some of it later gets picked up by the nozzle and then it burns there eventually leaving black marks on the print. This is very noticeable as I am printing in white ABS.
Printing settings:
layer height 0.25, 50mm/s @ 260 degrees C
bed initially at 110 degrees C lowered gradually to 90 degrees C
fan at 10% @ about 1mm height
The high temperature is needed as the part must be very strong. Also the parts are very large utilising almost the whole build area.
Any hints what other people are using for retraction? What are the maximum safe limits of the retraction values?
Thanks in advance for any hints.

Hi
I have recently moved onto ABS from PLA. I was not sure how fast I could print so I did the "Can your UM2 printer achieve 10mm3/s" with ABS. No issues reaching 10mm^3/s at 260 degrees C, ABS seems to flow much better than PLA.
So I tried printing an object at 7mm^3/s and the printer run for about an hour before it suddenly stopped extruding. Before I knew what was happening the nozzle was blocked and the filament was ground on the feeder.
After declogging the nozzle I tried printing something else, again at 7mm^3/s. It printed for <20min when I noticed that it started severely underextruding. No clicking from the feeder but hardly anything was coming out of the nozzle. I lowered the printing speed to 80% and things went back to normal.
After that I printed several objects at 5mm^3/s without issues.
I should note that all objects were quite simple with hardly any retractions.
So, why do I get underextrusion/clogging after while when printing faster?